Most homes and commercial buildings utilize electrical wiring systems to distribute power throughout the structure. Typically, electrical wiring systems carry a 120 or 240 volt signal at 15 or 30 amps, respectively, to provide electrical power for lighting systems, climate control systems, appliances, and other electrical loads. Many accidents occur annually due to penetrations of electrical wires or due to deterioration of older wiring systems.
According to reports issued by the Consumer Products Safety Commission (CPSC) in 1997, home wire systems caused over 40,000 fires that resulted in 250 deaths and over $670 million of property damage. Further study by the CPSC based on 40,300 electrical circuit fires showed that 36% were due to installed wiring and 16% were due to cord/plugs.
Today, circuit breakers primarily protect against certain overload and short circuit conditions which occur primarily in fixed wiring. The overload protection is provided by the slow heating of a bimetal strip that breaks the circuit causing the breaker to trip after a specified period of time. The more current that runs through the bimetal, the shorter the time it takes to trip the breaker. Short circuit protection may be provided magnetically, that is, a high level of current may trip a breaker instantaneously. The lower limit of the magnetic trip setting may be determined by the manufacturer such that the device does not nuisance trip on high inrush loads.
Circuit breakers do not protect against all hazards that may occur within electrical wiring systems. Therefore, in addition to circuit breakers, there are many other safety devices that have been designed for use with electrical wiring. One such safety device that is commonly installed in electrical wiring systems is a Ground Fault Circuit Interrupter (GFCI). A GFCI measures the difference between the currents flowing through the hot conductor and the neutral conductor of a conventional electrical wire. If the difference between the current flowing through the hot conductor and the current flowing through the neutral conductor exceeds a few milliamps, the presumption is that current is leaking to ground via some other path. This may be because of a short circuit to, for example, the chassis of an appliance, or to the ground lead, or through a person. Any of these situations may be hazardous, so the GFCI trips, breaking the circuit.
Another safety device that is commonly installed in electrical wiring systems is an Arc Fault Circuit Interrupter (AFCI). An AFCI adds electronic protection to the standard thermal and magnetic protection provided by circuit breakers. The circuitry in an AFCI detects specific arcs that are determined to be likely to cause a fire. The AFCI uses electronics to recognize the current and voltage characteristics of the arcing faults on the electrical wire, and interrupts the circuit when a fault is detected. Each AFCI has circuit logic, and perhaps control logic, that is designed to detect specific types of arc faults. These arc faults are specific to the type of wiring the AFCI is designed to be implemented with.
A problem with many electrical wire safety devices is that they are specifically designed to be used in conjunction with conventional three-conductor electric wire. Current safety devices are not designed to be used in wiring systems that include flat electrical wire. A flat electrical wire and method of fabricating the electrical wire are described in U.S. patent application Ser. No. 10/790,055 (Now U.S. Pat. No. 7,145,073), which is incorporated by reference herein in its entirety. Flat electrical wire is designed to be a surface-mounted wiring system that can be installed on surfaces such as a wall, ceiling or floor. Accordingly, flat electrical wire is designed to be thin and flexible in order to allow it to be easily concealed, for example, by being painted or papered over. Currently existing safety devices are not specifically designed to be used in conjunction with and in many cases are incompatible with flat electrical wire. Accordingly, a need exists for one or more safety devices that are suitable for use with flat electrical wire.
Another problem with many electrical wire safety devices is that they require manual intervention and/or manual reset once a fault is detected. The electrical wire safety devices are not capable of making a determination of when a fault is no longer present on a monitored wire and, therefore, will maintain the wire in a de-energized state. This inability to determine when a fault is no longer present can lead to undesirable situations. For example, an electrical wire that provides power to a refrigerator or freezer may be de-energized by an electrical wire safety device and, if a user does not reset the safety device, perishable food items may spoil. Accordingly, a need exits for one or more improved safety devices that are capable of determining when a fault is no longer present within a monitored wire or within a portion or all of a monitored wiring system.